Process vessel and piping system cleanliness, in many industries, is governed by strict regulatory requirements and standards. In certain industries, such as the food processing, dairy, and pharmaceutical industries, vessel cleaning and system cleaning must be performed regularly or daily to maintain sanitary standards and to meet strict regulatory requirements. In addition, in these, as well as other industries, vessels and piping systems may also require cleaning to permit maintenance on the vessels or systems, or subsequent to maintenance thereon.
To meet such cleanliness requirements in the most effective and cost efficient manner, many facilities, and in particular processing facilities which require regular or daily cleaning, have installed "clean-in-place" systems. These systems are usually permanent, fixed, "hard-piped" systems which operate to clean process systems quickly and without temporary piping, hoses, pumps, and the like.
Typically, clean-in-place systems comprise a number of tanks and associated pumps, automatic and manual valves, and interconnecting piping. The systems generally fall into two broad categories, namely single use systems in which the chemical cleaning agent is used once and discarded after use and multiple use systems in which the chemical cleaning agent is stored after use and subsequently reused for system cleaning. Single use systems can be configured as single tank or multi-tank systems. Such systems may include an eductor pump located at the clean-in-place unit to return the cleaning agent to the system, or motive pump return systems.
An exemplary two tank, eductor pump system includes a wash tank, a rinse tank, and a supply pump for supplying wash or rinse liquid to the vessel being washed. The two tank, eductor pump system also includes a motive tank in addition to the wash and rinse tanks, as well as a motive pump to provide dynamic head for the eductor. Thus, such a two tank, eductor pump system requires three tanks and two pumps, besides an eductor.
An exemplary, two tank, return pump system includes a wash tank, a rinse tank, a supply pump, and a return pump. The supply pump supplies the wash or rinse liquid to the vessel to be cleaned and the return pump returns the contaminated liquid from the vessel to the clean-in-place system. Return pump systems are more prevalent in those industries which use clean-in-place systems.
Three tank systems are designed and operated similarly, except that, in general, the additional tank provides the ability to supply an acid or a caustic solution to the vessel, as required for a particular application.
Clean-in-place systems are cost effective. Operating time for the clean-in-place system and downtime for the process system are minimized because clean-in-place systems are permanently installed to the processing system. Moreover, clean-in-place systems provide superior results as compared to manual cleaning. Thus, clean-in-place systems provide a more effective and flexible cleaning process with respect to time and cleanliness.
Nevertheless, there are some disadvantages associated with presently used clean-in-place systems. Clean-in-place systems which are currently used in industry can be cost intensive. The equipment, including tanks, pumps, valves, controls, and piping may be costly to purchase, particularly since such systems are fabricated, totally or in part, from stainless steel, or the like. Moreover, equipment costs for tanks, pumps, valves, and controls are often only a fraction of the cost for installing such equipment.
Additionally, operating costs for multi-tank clean-in-place systems can be high. Such operating costs include the cost of chemical cleaning agents which can be particularly high for single use systems in which the cleaning agent is used once and discarded. Further costs to be considered are those associated with providing supply water for the cleaning operation, as well as those associated with processing waste water. Given that the multi-tank systems are generally large volume based systems, the overall chemical cleaning agent and water costs can accumulate quickly.
Accordingly, clean-in-place systems are provided which use a single recirculation pump to provide vessel supply or feed solution and to return contaminated vessel wash solution, and which systems do not require, under most conditions, require additional tankage. Such systems minimize the initial cost of purchasing and installing an equipment intensive clean-in-place system, and further minimize the amount of chemical cleaning agent required to clean the vessels and piping systems by eliminating, to the extent possible, excess tankage. Moreover, the elimination of excess tankage also results in minimized water use and waste water processing.